1. Field of the Invention
The present invention relates to a device for moving or transferring objects within a chamber or between sealed chambers, specifically to such a device which combines rotary and translatory motions and can move samples within a vacuum deposition chambers or can transfer samples from one vacuum chamber to another.
2. Cross-References to Related Applications
My U.S. patent application Ser. No. 865,233, filed May 20, 1986, now U.S. Pat. No. 4,683,763, and entitled "Rotary-Motion Feed-Through Apparatus" and my other U.S. patent application Ser. No. 008,661, filed Jan. 1, 1987 and entitled "Gate Valve with Camming Wedge and Pressure Equilizer" cover devices which are closely related to the present invention.
3. Description of the Problem
It is often desirable or necessary to move objects within a closed chamber, such as a vacuum chamber. Such movement usually is done by a shaft which extends into the chamber so that translatory and rotary motions can be imparted into the chamber via the shaft from outside the chamber. The chamber should remain sealed at all times so as to constitute a closed system. This is especially true in vacuum chambers where it would be clearly impractical to shut the system down merely to rotate the shaft or move it in an axial direction.
One example of the need to move objects within a vacuum chamber occurs when it is necessary or desirable to change the position of a semiconductive substrate or test specimen with respect to a measuring instrument or ray emitting device, such as an electron beam gun which is located in predetermined axial and angular positions with respect to the substrate. Feed-through mechanisms or manipulators have been known and used in the past for these purposes.
One such mechanism is described in U.S. Pat. No. 2,973,107 to G. Cherel, 1961. The mechanism comprises a manipulator for sealed chambers in which rotary and translatory motions are transmitted, via rotatable and axially moveable magnets, to a holder which carries an object. One magnet is attached to a driving element outside the chamber and another to a driven element inside the chamber. Movements of the outside magnet are controlled via geared shafts.
Although the use of magnets eliminates seals and sliding parts, Cherel's device has a very complicated design and can provide displacements for only small distances and rotation within only small angles. Cherel's device is not a universal or self-contained device and is intended only for a specific application. In other words, it is not compatible with any other system and cannot be replaced by other similar devices or installed in field. Also the control element of this device uses complicated movements and is designed specially for manual control operations. Therefore Cherel's device is unsuitable for automatic, programmed control.